I have something like this:
assertThat(someList).extracting("someField")
and I want to continue the assert with asserting that only duplicates exist in the extraction. Is there a good way to do this?
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Mark Rotteveel
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Hans Wurst
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So assert that all elements of a list are the same? – Federico klez Culloca Sep 16 '22 at 08:41
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@FedericoklezCulloca exactly – Hans Wurst Sep 16 '22 at 08:42
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1`list.size() > 1 && new HashSet<>(list).size() == 1`. – Andy Turner Sep 16 '22 at 08:42
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@AndyTurner I rephrased my question. – Hans Wurst Sep 16 '22 at 08:50
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@HansWurst I don't know AssertJ, so I can't say exactly how to do it. First, assert that the list isn't empty; then, separately, assert that the size of `new HashSet<>(list)` is 1. – Andy Turner Sep 16 '22 at 08:52
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@AndyTurner this is definitely an option but I'm specifically interested in a solution using the AssertJ API. There is e.g. a method `doesNotContainDuplicates` – Hans Wurst Sep 16 '22 at 09:01
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@HansWurst I don't think your requirement is common enough to expect such a method to exist. – Andy Turner Sep 16 '22 at 09:51
1 Answers
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If you know what value is expected, containsOnly could be an option:
Verifies that the actual group contains only the given values and nothing else, in any order and ignoring duplicates (i.e. once a value is found, its duplicates are also considered found).
Extending your example:
List<SomeObject> someList = List.of(
new SomeObject("someValue"),
new SomeObject("someValue")
);
assertThat(someList)
.extracting("someField")
.containsOnly("someValue");
Stefano Cordio
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